The present invention relates to a transmission belt for a continuously variable transmission. The present invention also relates to a transmission and to a vehicle wherein such a transmission belt is applied.
Such a transmission belt is generally known, e.g. from EP-A-0.522.612. The elements in the known belt show a lower, or radially inner part that is tapered or is any other way recessed with respect to an upper, or radially outer part. The radially outer part of the elements shows a principal plane by which the elements transmit a pushing force from one to the other in a pushing trajectory part of the belt when it crosses from a first pulley to a second pulley of the transmission. A transition from this principal plane to the recessed lower part is commonly referred to as a rocking edge. The recessed lower part allows adjacent elements to mutually tilt about a contact line on the rocking edge over a certain tilting angle, so that the belt may pass along a curved, i.e. bent trajectory part between sheaves of a pulley of the continuously variable transmission. In the known belt the rocking edge extends over the axial width of the element and shows a curvature in the radial direction of the belt having a radius of about 6 mm, which in the known automotive conforms to the radius of curvature that develops as a stable value after initial, or run in wear of the element.
The transmission realises a continuously variable speed ratio between the first and the second pulley by varying a radius of the bent trajectory part for each of said pulleys in a coordinated manner. The transmission is said to have a ratio coverage, i.e. a measure for the range of speed ratios attainable by the transmission, which is usually defined as the squared value of the quotient of a maximum and the minimum radius of the said bent trajectory part, whereby said radii of the bent trajectory parts are determined by the radial position of the contact line. A large ratio coverage is advantageous for the efficiency of and driving comfort associated with a motor vehicle in which the transmission is to be applied.